1. Field of the Invention
The present invention relates to a fabricating system having a film formation system for depositing materials which can be deposited by vapor deposition (hereinafter, an evaporation material), a light-emitting device which has a organic compound containing layer made as a light emitting layer using the fabricating system and a fabricating method thereof. Specifically, the present invention relates to a film formation method (a vapor deposition method) and a fabrication system for forming a film by vaporizing an evaporation material from a plurality of evaporation sources provided to be opposite to a substrate.
2. Description of the Related Art
In recent years, research related to a light-emitting device having an EL device as a self-luminous light emitting device has been activated. The light-emitting device is referred to as organic EL display or organic light-emitting diode. Since these light-emitting devices have characteristics such as rapid response speed that is suitable for moving picture display, low voltage, low power consumption driving, they attracts an attention for a next generation display including new generation's mobile phones and portable information terminals (PDA).
The EL device has an organic compound containing-layer as a light-emitting layer. The EL device has a structure that the organic compound-containing layer (hereinafter, referred to as an EL layer) is sandwiched between an anode and a cathode. Electro luminescence is generated in the EL layer by applying an electric field to the anode and the cathode. Light emission obtained from the EL device includes light emission in returning to a base state from singlet excitation state (fluorescence) and light emission in returning to a base state from triplet excitation state (phosphorescence).
The EL layer has a laminated structure typified “a hole transporting layer, a light-emitting layer and an electron transporting layer.” EL material for forming an EL layer is classified broadly into a low-molecular (monomer) material and high-molecular (polymer) material. The low-molecular material is deposited using a vapor deposition system.
The existing vapor deposition system has a substrate holder where a substrate is set, a crucible encapsulating an EL material, in other words an evaporation material, a shutter to prevent the EL material to be sublimed from rising, and a heater for heating an EL material in a crucible. Then, the EL material heated by the heater is sublimed and deposited on a rolling substrate. At this time, in order to deposit uniformly, the distance between the substrate and the crucible needs to be 1 m or more.
According to the above-described vapor deposition system and the above-described vapor deposition method, when an EL layer is formed by vapor deposition, almost all of the sublimated EL material is adhered to an inner wall, a shutter or an adherence preventive shield (a protective plate for preventing a evaporation material from adhering to an inner wall of a deposition chamber) at inside of the deposition chamber of the vapor deposition system. Therefore, in forming the EL layer, an efficiency of utilizing the expensive EL material is extremely low i.e. about 1% or less and fabricating cost of a light-emitting device becomes very high.
Further, according to the vapor deposition system of the related art, in order to provide a uniform film, it is necessary to separate a substrate from an evaporation source by an interval equal to 1 m or more. Therefore, the vapor deposition system per se grows in size, a period required for exhausting each deposition chamber of the vapor deposition system is prolonged and therefore, a film formation speed is slowed down and throughput is lowered. Also, in using a large area substrate, it may be a problem that the film thickness between a center portion and a marginal portion of a substrate is uneven. Further, the vapor deposition system has a structure for a rotation of a substrate and therefore, there is a limit in the vapor deposition system aiming at a large area substrate.
Further, there is a problem that the EL material is easily oxidized and deteriorated due to a presence of oxygen or water. However, in forming a film by a vapor deposition method, a predetermined amount of a evaporation material put into a vessel (glass bottle) is taken out and transferred to a vessel (representatively, crucible, or vapor deposition boat) installed at a position opposite to an object to be deposited at inside of a vapor deposition system and there is a concern that the evaporation material is mixed with oxygen or water or an impurity in the transferring operation.
Further, when the evaporation material is transferred from the glass bottle to the vessel, the evaporation material is transferred by human hands with a glove or the like at inside of a pretreatment chamber of a deposition chamber provided with a glove or the like. However, when the glove is provided at the pretreatment chamber, the chamber cannot be subjected to vacuum, the operation is carried out under atmospheric pressure and there is a high possibility of mixing an impurity. Even when the transferring operation is carried out at inside of the pretreatment chamber subjected to a nitrogen atmosphere, it is difficult to reduce moisture or oxygen as little as possible. Further, although it is conceivable to use a robot, since the evaporation material has a powder-like shape and therefore, it is very difficult to fabricate the robot for carrying out the transferring operation. Therefore, it is difficult to perform steps of forming an EL device, in other words, from a step of forming an EL layer above a lower electrode to a step of forming an upper electrode, by an integrated closed system preventing an impurity from being mixed.
Hence, the present invention provides a vapor deposition system of fabricating systems that promote an efficiency of utilizing an EL material and is excellent in uniformity or throughput of forming an EL layer and a vapor deposition method. Further, the present invention provides a light-emitting device fabricated by the vapor deposition system and the vapor deposition method according to the present invention and a method of fabricating the light-emitting device.
Further, the present invention provides a fabricating system for vapor-depositing an EL material efficiently to a large area substrate having a size of, for example, 320 mm×400 mm, 370 mm×470 mm, 550 mm×650 mm, 600 mm×720 mm, 680 mm×880 mm, 1000 mm×1200 mm, 1100 mm×1250 mm or 1150 mm×1300 mm. Also, the present invention provides a vapor deposition system that makes a whole surface of a large area substrate uniform with even thickness.
Further, the present invention provides a fabricating system capable of preventing an impurity from being mixed into an EL material.